Process and composition for impregnating wood



Patented Nov. 8, 1932 UNITED STATES PATENT OFFICE O. NIELSEN, OF mPHIS, TENNESSEE, ASSIGNOB "1'0 NATIONAL WOOD PRODUCTS COMPANY, OF DETROIT, MICHIGAN, A CORPORATION 01 DELAWARE PROCESS AND COMPOSITION FOR IHPBEGNATING WOOD Io Drawing.

The present invention relates to a method and composition for impregnating wood, and it is applicable to all kinds of wood, whether for the purpose of rendering the wood unalterable in ordinary atmosp eric conditions or for coloring the wood or for preserving the wood a ainst decay, attack of insects, termites, tere o, fungi and the like.

A further object is the employment of a composition whlch will comp etely impregnate the wood, at a relatively low temperature such as 125 to 135 F. The impregnation under these conditions will be suflicient- 1y complete in 2 to 8 hours dependingupon the particular kind of wood and the d1mensions of the wood, and after drying for about 4 to 8 da s the wood will be found hard and will be ound to be capable of taking an kind of surface coatin as may be desire The wood is also thereiy' protected against wet and dry rot, and against moisture. The treated wood will not absorb moisture and -accordingly will not swell, shrink, check,

cur1,but becomes permanent. I

For the purpose of more fully explaining the nature of the process, the following is ven- Preferred illustrative formula (parts by volume).

15% yellow neutral mineral oil of lubrieating grade,

36% mineral spirits,

10% manganese drying oil,

10% gloss oil (6 parts of rosin dissolved in about 4 arts of mineral spirits),

% woo turpentine (preferably steam distilled, rectlfied, water-white) 5% orthodichlorbenzene,

2% strong formaldehyde solution,

"2% of mixture of 2 parts chromealum and 1 part oil-soluble anilin dye).

It'will' be understood that the roportions here given are those which have een found by me to be generally most suitable, but it will understood that these proportions are subject to more or less variation. The yellow neutral mineral oil of lubricating grade may be used to the extent of from 10 to 17% more or less, and while I prefer ordinarily Application filed larch 14, 1929. Serial No. 847,174.

to use a yellow oil, it will be understood that the use of a brown or black oil is not p recluded, particularly when color is of no objection in the finished product. The amount of mineral spirits and the amount of wood turpentine as given in the above formula amounts to 56%. However the combined amounts of these materials may vary between about and about 65% of the whole, and if desired the proportion of the wood turpentine to mineral spirits may vary more or ess.

The amount of manganese drying oil (made by cooking up a drying oil such as linseed oil with manganese dioxide or other manganese compound) can vary from about 8% to about 1 1%.

In place of orthodichlorbenzene a mixture of the dichlorbenzenes may be employed, and the amount of 5%can be substantially varied,

for example between 2% and 7%. The

amount of the strong formaldehyde solution (preferably a 35 or 40% solution bein employed) can be varied between about 1 0 and about 3%, giving satisfactory results. The chrome alum referred to has been found to be most suitable 1n the process but other alums can be employed. The above formula employs about 1.3% of chrome alum but the amount can vary from about 1 to 2%. The oil-soluble anilin dye is given as the most satisfactory, if a dye 1s to be employed. When it is deslred to have the wood uncolored after treatment, the dye can of course be omitted. When odor is not ob'ectionable and when preserving of the woo is a main consideration, as in the treatment of cross-ties, telephone poles, pilings, planking, bridge timbers and the like, in place of the anilin dye or in addition thereto if desired, a considerable amount of a tarry material may be employed. For example 30 parts of coal tar may be suitable in 100 arts of the above formula.

The lmpregnating process may conveniently be carried out in open tanks. I find it advisable to submerge the wood in the tank or vat of the warm impregnating material, at a temperature of about 125 F. The solution is preferably kept at near this temperature, under which conditions the penetration will be found to be quite rapid. The heat may be gradually increased during the impregnation period, and the wood may be removed from the bath when the latter is about 135 F.

For preparing the wood treating composition from the above Components, I preferably place the alum in the formaldehyde solution for say 8 hours, the alum being preferably in a finely ground condition, and the mixture being stirred frequently, during this period. I find it most advisable not to heat at any time during the impregnation to above 135 F., under which conditions the wood is not in any way injured. I am aware that heretofore various mixture have been used for the impregnation of wood, and generally temperatures very much higher than those above indicated have been employed, with a consequent detriment in the quality of the wood.'

After removing the wood from the treating bath, it can be stored for 4.- to 8 days or longer in a suitable dryingshed, in order to allow complete drying of the wood. The drying includes oxidation of a certain proportion of the material, including the manganese drying oil and perhaps some of the other constituents. After drying, and particularly in case the tar has not been used as a component of suitable manner. The manganese drying oil,

gloss oil and to some extent the turpentine contribute to the drying properties of the material. The turpentine and mineral spirits are both readily volatile, and produce quick evaporation of the solvent matter from the impregnated wood.

The formaldehyde has the effect of setting the color, and also acts as a solvent for the chrome alum or other alum employed. It also has some hardening effect on the wood. The alum not only has its useful effects on the wood fibre, but also acts to set the color and prevent fading of the color.

The color preferably employed should be readily soluble in oil and oily mixtures, and should be a dye which is itself relatively fast, in order that the color of the products should be permanent.

The coal tar is particularly used in the case of timbers, poles, ties, piles, sub fiooring and the llke, and exercises a powerful preservative and protective action upon the Wood, during use of the latter.

I call attention to the fact that the impregnating fluid, applied in the manner above described, penetrates throughout the body of the wood. Coloring matter in the solution is thereby carried throughout theentire body of the wood, and as the wood wears away or is sandpapered down or is planed down, the color will be found to remain.

When using the proportions as above ind1- cated, in the impregnating liquid, there is no substantial amount of bleeding or oozlng out of the oily material after the initial drying. This is due to the fact that I do not leave the pores of the wood filled up with the impregnating medium, but the cell walls are coated and impregnated therewith.

I have above referred to applying finlsh coatings to the impregnated material. When the impregnated material is flooring, panels, blocks for flooring and the like, the impregnated material after the initial drying may be first planed or sandpapered if desired and necessary, after which it can then be coated with a lacquer varnish, which adheres extremely well to the treated wood, and does not show any tendency to separate or peel off, even after a long period.

In coating with lacquer, it is of course unnecessary to use any pigments in the lacquer if a transparent finish is desired. This'is of importance both in connection with wood which has been impregnated with the solution containing a dye, and also in the case of wood which has been impregnated with the clear solution without a dye. The use of dyes in this manner, followed by dressing the lumber as by planing or sandpapering, and then lacquering, produces a very beautiful finish whereby very cheap woodscan be made to imitate, rare and expensive woods, this being particularly suitable for inside work such as flooring, interior trim, panels, Wainscoting, doors, furniture and the like.

To get the best results, the wood should be relatively dry, before the treatment. I prefer to first dry the wood down to about a 5 to 7% moisture content, this being efiected if desired in a drying kiln. While these fi ures are subject to some variation, I strong y recommend drying the wood, before the impregnation to about 3 to 9% moisture content.

I claim ..1. In the treatment of wood, the herein described process which comprises immersing the wood in a dry state in a liquor containing'neutral mineral oil, mineral spirits, manganese drying oil, turpentine, rosin, dichlor benzol, formaldehyde and an alum, the mineral spirits and turpentine amounting to about 50-65% of the whole, the neutral mineral oil being about 10 to 17%, the manganese drying oil being about 8 to 11% and the other materials' being in small but substantial amounts, the treatment being conducted at about to F., until the wood is sufliciently permeated with the mlxture.

2. Process as in claim 1, in which an oilsoluble coloring material is added.

3. Process as per claim 1, in which tarry material, to the amount of 20 to 35% is added as the coloring material.

4. A composition for impregnating wood comprising 10 to 17% of neutral mineral 011,

'55. to 65% of mineral spirits and turpentine,

15 parts neutral mineral oil,

36 parts mineral spirits,

10 parts manganese drying oil,

10 parts gloss oil,

20 parts turpentine,

5 parts orthodichlorbenzene, 2 parts formaldehyde solution and about 1 to 2 parts of chrome alum.

8. Composition as per claim 7, with. about 0.5 to 1 part of an oil-soluble dye added.

9. Composition as per claim 7 with a sub- I stantial amount of tar added.

10. Wood impregnated with the composition as covered in claim 4,'dried and carrying a dried coating of a transparent lacquer.

11. Wood impregnated with the compositlon as covered in claim 4, and an oil-soluble dye, dried and carrying a dried coating of a transparent lacquer.

In testimony whereof aflix my signature.

HERMAN G. NIELSEN. 

